In 1939, Britain and France offered military support to Poland in the likely case of a German invasion. In the dawn of 1 September 1939, the German Invasion of Poland began. France and the United Kingdom declared war on 3 September, after an ultimatum for German forces to immediately withdraw their forces from Poland was met without reply. Following this, Australia (3 September), New Zealand (3 September), South Africa (6 September) and Canada (10 September), declared war on Germany. British and French commitments to Poland were met politically but they adopted a long-war strategy and mobilised for defensive land operations against Germany, while a trade blockade was imposed and the pre-war re-armament was accelerated, ready for an eventual invasion of Germany.
On 7 September, in accordance with their alliance with Poland, France began the Saar Offensive with an advance from the Maginot Line 5 km (3.1 mi) into the German-occupied Saar. France had mobilised 98 divisions (all but 28 of them reserve or fortress formations) and 2,500 tanks against a German force consisting of 43 divisions (32 of them reserves) and no tanks. The French advanced until they met the then thin and undermanned Siegfried Line. On 17 September, the French supreme commander, Maurice Gamelin gave the order to withdraw French troops to their starting positions; the last of them left Germany on 17 October. Following the Saar Offensive, a period of inaction called the Phoney War (the French Drôle de guerre, joke war or the German Sitzkrieg, sitting war) set in between the belligerents. Adolf Hitler had hoped that France and Britain would acquiesce in the conquest of Poland and quickly make peace. On 6 October, he made a peace offer to both Western powers. Even before they had time to respond, on 9 October, he also formulated a new military policy, in case their reply was negative, "Führer-Directive Number 6" (Führer-Anweisung N°6).
Hitler recognised the necessity of military campaigns to defeat the Western European nations, preliminary to the conquest of territory in Eastern Europe, to avoid a two-front war but these intentions were absent from Directive N°6. The plan was based on the seemingly more realistic assumption that German military strength would have to be built up for several years. For the moment only limited objectives could be envisaged and were aimed at improving Germany's ability to survive a long war in the west. Hitler ordered a conquest of the Low Countries to be executed at the shortest possible notice. This would forestall the French and prevent Allied air power from threatening the vital German Ruhr Area. It would also provide the basis for a long-term air and sea campaign against Britain. There was no mention in the Führer-Directive of any immediate consecutive attack to conquer the whole of France, although the directive read that as much as possible of the border areas in northern France should be occupied.
At first, Hitler proposed beginning the invasion on 25 October 1939 but accepted that the date was probably unrealistic. On 5 November, he informed Walther von Brauchitsch that he planned for the invasion to begin on the 12 November. The general replied that the military had largely not recovered from the Polish campaign; the motorised units had to recover, repairing the damage to their vehicles and ammunition stocks were largely depleted. Brauchitsch offered to resign if Hitler did not change his mind. His resignation was refused but two days later Hitler postponed the attack, providing poor weather as the official reason for the delay.
On 10 October 1939, Britain refused Hitler's offer of peace and on 12 October, France did the same. Colonel-General Franz Halder (Chief of the General Staff of OKH), presented the first plan for Fall Gelb (Case Yellow) on 19 October. This was the pre-war codename of plans for a campaign in the Low Countries: the Aufmarschanweisung N°1, Fall Gelb (Deployment Instruction No. 1, Case Yellow). Halder's plan has been compared to the Schlieffen Plan, the name given to the German strategy of 1914 in the First World War. It was similar in that both plans entailed an advance through the middle of Belgium. Aufmarschanweisung N°1 envisioned a frontal attack, sacrificing a projected half million German soldiers to attain the limited goal of throwing the Allies back to the River Somme. Germany's strength for 1940 would then be spent; only in 1942 could the main attack against France begin. When Hitler raised objections to the plan and instead advocated for a decisive armoured breakthrough as had happened in the Invasion of Poland, both Halder and Army Commander-in-Chief General Walther von Brauchitsch attempted to dissuade him, arguing that while the fast-moving mechanised tactics were all well and good against a "shoddy" Eastern European army, they would not work against a first-rate military like the French.
Hitler was disappointed with Halder's plan and initially reacted by deciding that the German army should attack early, ready or not, in the hope that Allied unreadiness might bring about an easy victory. This led to a series of postponements, as commanders repeatedly persuaded Hitler to delay the attack for a few days or weeks, to remedy some critical defect in the preparations or to wait for better weather. Hitler also tried to alter the plan, which he found unsatisfactory; his weak understanding of how poorly-prepared Germany was for war and how it would cope with losses of armoured vehicles were not fully considered. Though Germany defeated Poland in a relatively short time, many armoured vehicles (mainly tanks) had been lost and were hard to replace. This eventually resulted in a dispersion of the German effort; although the main attack would remain in central Belgium, secondary attacks would be undertaken on the flanks. Hitler made such a suggestion on 11 November, pressing for an early attack on unprepared targets. On 29 October, Halder presented another plan, Aufmarschanweisung N°2, Fall Gelb, reflecting these changes by featuring a secondary attack on the Netherlands.
Hitler was not alone in disliking Halder's plan. General Gerd von Rundstedt, the commander of Army Group A, also disagreed with it. Rundstedt recognised that it did not adhere to the classic principles of the Bewegungskrieg (manoeuvre warfare) that had guided German strategy since the 19th century. A breakthrough would have to be accomplished that would result in the encirclement and destruction of the main body of Allied forces. The most practical place to achieve this would be in the region of Sedan, which lay in the sector of Rundstedt's Army Group. On 21 October, Rundstedt agreed with his chief of staff, Generalleutnant Erich von Manstein, that an alternative operational plan had to be arranged that would reflect these basic ideas, by making Army Group A as strong as possible at the expense of Army Group B to the north.
While Manstein was formulating new plans in Koblenz, Generalleutnant Heinz Guderian, commander of the XIX Army Corps, was lodged in a nearby hotel. Manstein was initially considering a move north from Sedan, directly in the rear of the main Allied mobile forces in Belgium. When Guderian was invited to contribute to the plan during informal discussions, he proposed a radical and novel idea. Most of the Panzerwaffe should be concentrated at Sedan. This concentration of armour should advance to the west to the English Channel, without waiting for the main body of infantry divisions. This might lead to a strategic collapse of the enemy, avoiding the relatively high number of casualties normally caused by a Kesselschlacht (cauldron battle).
Such a risky independent use of armour had been widely discussed in Germany before the war but Oberkommando des Heeres (OKH, the German General Staff), doubted such an operation could work. Manstein's general operational ideas won immediate support from Guderian, who understood the terrain, having experienced the conditions with the German Army in 1914 and 1918. Manstein wrote his first memorandum outlining the alternative plan on 31 October. In it he avoided mentioning Guderian and played down the strategic part of the armoured units, to avoid unnecessary resistance. Six more memoranda followed between 31 October 1939 and 12 January 1940, each becoming more radical. All were rejected by OKH and nothing of their content reached Hitler.
On 10 January 1940, a German aircraft carrying a staff officer with the Luftwaffe plans for an offensive through central Belgium to the North Sea, force-landed near Mechelen in Belgium. The documents were captured but Allied intelligence doubted that they were genuine. In the full moon period in April 1940, another Allied alert was called for a possible attack on the Low Countries or Holland, an offensive through the Low Countries to outflank the Maginot Line from the north, an attack on the Maginot Line or an invasion through Switzerland. None of the contingencies anticipated the German attack through the Ardennes but after the loss of the Luftwaffe plans, the Germans assumed that the Allied appreciation of German intentions would have been reinforced. Aufmarschanweisung N°3, Fall Gelb an amendment to the plan on 30 January, was only a revision of details but on 24 February, the main German effort was switched south to the Ardennes. Twenty divisions (including seven panzer and three motorised divisions) were transferred from Heeresgruppe B (Army Group B) opposite Holland and Belgium to Heeresgruppe A (Army Group A) facing the Ardennes. French military intelligence uncovered a transfer of German divisions from the Saar to the north of the Moselle but failed to detect the redeployment from the Dutch frontier to the Eiffel–Moselle area.
On 27 January, Manstein was sacked as Chief of Staff of Army Group A and appointed commander of an army corps in East Prussia. To silence Manstein, Halder had instigated his transfer to Stettin on 9 February. Manstein's staff brought his case to Hitler, who had independently suggested an attack at Sedan, against the advice of OKH. On 2 February, Hitler was told of Manstein's plan and on 17 February, Hitler summoned Manstein, generals Rudolf Schmundt (Chief of Personnel of the German army) and Alfred Jodl, the Chief of Operations at Oberkommando der Wehrmacht (OKW, German armed forces high command), to attend a conference. The next day, Hitler ordered Manstein's thinking to be adopted, because it offered the possibility of decisive victory. Hitler recognised the breakthrough at Sedan only in tactical terms, whereas Manstein saw it as a means to an end. He envisaged an operation to the English Channel and the encirclement of the Allied armies in Belgium; if the plan succeeded, it could have a strategic effect.
Halder then went through an "astonishing change of opinion", accepting that the Schwerpunkt should be at Sedan. He, however, had no intention of allowing an independent strategic penetration by the seven panzer divisions of Army Group A. Much to the dismay of Guderian, this element was absent from the new plan, Aufmarschanweisung N°4, Fall Gelb, issued on 24 February. Halder was criticised in the same way he had attacked Manstein, when he first proposed his attack plan. The bulk of the German officer corps was appalled and called Halder the "gravedigger of the Panzer force". Even when adapted to more conventional methods, the new plan provoked a storm of protest from the majority of German generals. They thought it utterly irresponsible to create a concentration of forces in a position impossible adequately to supply, along routes that could be cut easily by the French. If the Allies did not react as expected, the German offensive could end in catastrophe. Their objections were ignored and Halder argued that, as Germany's strategic position seemed hopeless anyway, even the slightest chance of decisive victory should be grasped.
On 3 September 1939, French military strategy had been settled, taking in analysis of geography, resources and manpower. The French army would defend on the right and advance into Belgium on the left, to fight forward of the French frontier. The extent of the forward move was dependent on events, which had been complicated when Belgium ended the Franco-Belgian Accord of 1920 after the German Remilitarization of the Rhineland (7 March 1936). As a neutral, the Belgian state was reluctant to co-operate openly with France but did communicate information about Belgian defences. By May 1940, there had been an exchange of the general nature of French and Belgian defence plans but little co-ordination, especially against a possible German offensive westwards through Luxembourg and the east of Belgium. The French expected Germany to breach Belgian neutrality first, providing a pretext for French intervention or that the Belgians would request support when an invasion was imminent. Most of the French mobile forces were assembled along the Belgian border, ready forestall the Germans.
An early appeal for help might give the French time to reach the German–Belgian frontier but if not, there were three feasible defensive lines further back. There was a defensible line from Givet to Namur, across the Gembloux Gap (la trouée de Gembloux), Wavre, Louvain and along the Dyle river to Antwerp, which was 70–80 km (43–50 mi) shorter than the alternatives. A second possibility was a line from the French border to Condé, Tournai, along the Escaut (Scheldt) to Ghent and thence to Zeebrugge on the North Sea coast, possibly further along the Scheldt (Escaut) to Antwerp, which became the Escaut Plan/Plan E. The third possibility was along field defences along the French border from Luxembourg to Dunkirk. For the first fortnight of the war, Gamelin favoured Plan E, because of the example of the fast German advances in Poland. Gamelin and the other French commanders doubted that they could advance any further forward before the Germans arrived and in late September, Gamelin issued Général d'armée Gaston Billotte, commander of the 1st Army Group a directive for,
...assuring the integrity of the national territory and defending without withdrawing the position of resistance organised along the frontier....
giving the 1st Army Group permission to enter Belgium and deploy along the Escaut according to Plan E. On 24 October, Gamelin directed that an advance beyond the Escaut could only be possible if the French moved fast enough to forestall the Germans.
By late 1939 the Belgians had improved the defences along the Albert Canal and increased the readiness of the army; Gamelin and GQG began to consider the possibility of advancing further than the Escaut. By November, GQG had decided that a defence along the Dyle Line was feasible, despite the doubts of General Alphonse Georges, commander of the North-Eastern Front about reaching the Dyle before the Germans. The British had been lukewarm about an advance into Belgium but Gamelin talked them round and on 9 November, the Dyle Plan was adopted. On 17 November, a session of the Supreme War Council deemed it essential to occupy the Dyle Line and Gamelin issued a directive that day detailing a line from Givet to Namur, the Gembloux Gap, Wavre, Louvain and Antwerp. For the next four months, the Dutch and Belgian armies laboured over their defences, the British Expeditionary Force (BEF) expanded and the French army received more equipment and training. Gamelin also considered a move towards Breda in the Netherlands; if the Allies prevented a German occupation of Holland, the ten divisions of the Dutch army would join the Allied armies, North Sea communications would be enhanced and the Germans denied bases for attacks on Britain.
In May 1940, the 1st Army Group was responsible for the defence of France from the Channel coast to the west end of the Maginot Line. The Seventh Army (Général d'armée Henri Giraud), BEF (General Lord Gort), First Army (Général d'armée Georges Maurice Jean Blanchard) and Ninth Army (Général d'armée André Corap) were ready to advance to the Dyle Line, by pivoting on the right (southern) Second Army. The Seventh Army would take over west of Antwerp, ready to move into Holland and the Belgians were expected to delay a German advance, then retire from the Albert Canal to the Dyle from Antwerp to Louvain. On the Belgian right, the BEF was to defend about 12 mi (20 km) of the Dyle from Louvain to Wavre with nine divisions and the First Army on the right of the BEF was to hold 22 mi (35 km) with ten divisions, from Wavre across the Gembloux Gap to Namur. The gap from the Dyle to Namur north of the Sambre, with Maastricht and Mons on either side, had few natural obstacles and was a traditional route of invasion, leading straight to Paris. The Ninth Army would take post south of Namur, along the Meuse to the left (northern) flank of the Second Army.
The Second Army was the right (eastern) flank army of the 1st Army Group, holding the line from Pont à Bar 3.7 mi (6 km) west of Sedan to Longuyon. GQG considered that the Second and Ninth armies had the easiest task of the army group, dug in on the west bank of the Meuse on ground that was easily defended and behind the Ardennes, with plenty of warning of a German attack in the centre of the French front. After the transfer of the Seventh Army to the1st Army Group, seven divisions remained behind the Second and Ninth armies and other divisions could be moved from behind the Maginot Line. All but one division were either side of the junction of the two armies, GQG being more concerned about a possible German attack past the north end of the Maginot Line and then south-east through the Stenay Gap, for which the divisions behind the Second Army were well placed.
If the Allies could control the Scheldt Estuary, supplies could be transported to Antwerp by ship and contact established with the Dutch army along the Scheldt. On 8 November, Gamelin directed that a German invasion of the Netherlands must not be allowed to pass round the west of Antwerp by gaining the south bank of the Scheldt. The left flank of the 1st Army Group was reinforced by the Seventh Army, containing some of the best and most mobile French divisions, which moved from the general reserve by December. The role of the army was to occupy the south back of the Scheldt and be ready to move into Holland and protect the estuary by holding the north bank along the Beveland Peninsula (now the Walcheren–Zuid-Beveland–Noord-Beveland peninsula) in the "Holland Hypothesis". On 12 March 1940, Gamelin discounted dissenting opinion at GQG and decided that the Seventh Army would advance as far as Breda to link with the Dutch. Georges was told that the Seventh Army role on the left flank of the Dyle manoeuvre would be linked to it and Georges notified Billotte, that if it were ordered to cross into the Netherlands, the left flank of the army group was to advance to Tilburg if possible and certainly to Breda. The Seventh Army was to take post between the Belgian and Dutch armies by passing the Belgians along the Albert Canal and then turning east, a distance of 109 mi (175 km), against German armies only 56 mi (90 km) distant from Breda. On 16 April, Gamelin also made provision for a German invasion of only the Netherlands, by changing the area to be reached by the Seventh Army; the Escaut Plan was to be followed only of the Germans forestalled the French move into Belgium.
In the winter of 1939–40, the Belgian consul-general in Cologne had anticipated the angle of advance that Manstein was planning. Through intelligence reports, they deduced that German forces were concentrating along the Belgian and Luxembourg frontiers. The Belgians were convinced that the Germans would thrust through the hilly and heavily forested Ardennes and to the English Channel with the aim of cutting off the Allied field armies in Belgium and north-eastern France. They also anticipated that the Germans would try to land Fallschirmjäger (paratroops) and glider forces behind the Allied lines, to capture Belgian fortifications. Such warnings were not heeded by the French or British. In March 1940, Swiss intelligence detected six or seven Panzer divisions on the German-Luxembourg-Belgian border. More motorised divisions had also been detected in the area. French intelligence were informed through aerial reconnaissance that the Germans were constructing pontoon bridges about halfway over the Our River on the Luxembourg-German border. The French military attaché in Bern warned that the centre of the German assault would come on the Meuse at Sedan, sometime between 8 and 10 May. The report was dated 30 April. These reports had little effect on Gamelin, as did similar reports from neutral sources such as the Vatican, and a French sighting of a 100 km (62 mi)-long line of German armoured vehicles inside Germany to the Luxembourg border.
Germany had mobilised 4,200,000 men of the Heer, 1,000,000 of the Luftwaffe, 180,000 of the Kriegsmarine, and 100,000 of the Waffen-SS. When consideration is made for those in Poland, Denmark and Norway, the Army had 3,000,000 men available for the offensive on 10 May 1940. These manpower reserves were formed into 157 divisions. Of these, 135 were earmarked for the offensive, including 42 reserve divisions. The German forces in the west in May and June deployed some 2,439 tanks and 7,378 guns. In 1939–40, 45 percent of the army was at least 40 years old, and 50 percent of all the soldiers had just a few weeks' training. The German Army was far from fully motorised; just 10 percent of their army was motorised in 1940 and could muster only 120,000 vehicles, compared to the 300,000 of the French Army. The British had the most enviable contingent of motorised forces. Most of the German logistical transport consisted of horse-drawn vehicles. Only 50 percent of the German divisions available in 1940 were combat ready, often being more poorly equipped than their equivalents in the British and French Armies, or even as well as the German Army of 1914. In the spring of 1940, the German Army was semi-modern. A small number of the best-equipped and "elite divisions were offset by many second and third rate divisions".
The German Army was divided into Army Group A, commanded by Gerd von Rundstedt, was composed of 45 1⁄2 divisions, including seven armoured and was to execute the decisive movement through the Allied defences in the Ardennes. The manoeuvre carried out by the Germans is sometimes referred to as a "Sichelschnitt", the German translation of the phrase "sickle cut" coined by Winston Churchill after the events to describe it but never the official name of the operation. It involved three armies (the 4th, 12th and 16th) and had three Panzer corps. The XV, had been allocated to the 4th Army but the XXXXI (Reinhardt) and the XIX (Guderian) were united with the XIV Army Corps of two motorised infantry divisions on a special independent operational level in Panzergruppe Kleist (officially known as XXII Corps). Army Group B (Fedor von Bock), composed of 29 1⁄2 divisions including three armoured, was to advance through the Low Countries and lure the northern units of the Allied armies into a pocket. It consisted of the 6th and 18th Armies. Army Group C (Wilhelm Ritter von Leeb), composed of 18 divisions, was charged with preventing a flanking movement from the east and with launching small holding attacks against the Maginot Line and the upper Rhine. It consisted of the 1st and 7th Armies.
Wireless proved essential to German success in the battle. German tanks had radio receivers that allowed them to be directed by platoon command tanks which had voice communication with other units. Wireless allowed for last-minute changes in tactics and far quicker improvisation than the enemy. Some commanders regarded the ability to communicate to be the primary method of combat and radio drills were considered to be more important than accurate gunnery. Radio allowed German commanders to co-ordinate their formations, bringing them together for a mass firepower effect in attack or defence. The French advantage in numbers and equipment, which was often deployed in "penny-packets" (dispersed as individual support weapons) was offset. Most French tanks also lacked radios, and orders between infantry units were typically passed by telephone or verbally.
The German communications system permitted a degree of communication between air and ground forces. Attached to Panzer divisions were the Fliegerleittruppen (tactical air control troops) in wheeled vehicles. There were too few Sd.Kfz. 251 command vehicles for all of the army, but the theory allowed the army in some circumstances to call Luftwaffe units to support an attack. It is said the participants in the dash to the English Channel carried out by the XIX Panzer Corps never had to wait more than 15–20 minutes for the Luftwaffe to appear over a target after they had called. Fliegerkorps VIII, equipped with Junkers Ju 87 dive-bombers (Stukas), was to support the dash to the Channel if Army Group A broke through the Ardennes and kept a Ju 87 and a fighter group on call. On average, they could arrive to support armoured units within 45–75 minutes of orders being issued.
The main tool of the German land forces was combined arms combat. German operational tactics relied on highly mobile offensive units, with balanced numbers of well-trained artillery, infantry, engineer and tank formations, all integrated into Panzer divisions. They relied on excellent communication systems which enabled them to break into a position and exploit it before the enemy could react. Panzer divisions could carry out reconnaissance missions, advance to contact, defend and attack vital positions or weak spots. This ground would then be held by infantry and artillery as pivot points for further attacks. Although their tanks were not designed for tank-versus-tank combat, they could take ground and draw the enemy armour on to the division's anti-tank lines. This conserved the tanks to achieve the next stage of the offensive. The units' logistics were self-contained, allowing for three or four days of combat. The Panzer divisions would be supported by motorised and infantry divisions.
The German Army lacked a formidable heavy combat tank like the French Char B1. In armament and armour, French tanks were the stronger designs and more numerous (although the German vehicles were faster and more mechanically reliable). But while the German Army was outnumbered in artillery and tanks, it possessed some critical advantages over its opponents. The newer German Panzers had a crew of five men: a commander, gunner-aimer, loader, driver and mechanic. Having a trained individual for each task allowed each man to dedicate himself to his own mission and it made for a highly efficient combat team. The French had fewer members, with the commander double-tasked with loading the main gun, distracting him from his main duties in observation and tactical deployment. It made for a far less efficient system. Even within infantry formations, the Germans enjoyed an advantage through the doctrine of Auftragstaktik (mission command tactics), by which officers were expected to use their initiative to achieve their commanders' intentions, and were given control of the necessary supporting arms.
The Luftwaffe divided its forces into two groups. In total, 1,815 combat, 487 transport and 50 glider aircraft were deployed to support Army Group B, while a further 3,286 combat aircraft were deployed to support Army Groups A and C. The combined Allied total was 2,935 aircraft, about half the number of the German force. The Luftwaffe could provide close support with dive-bombers and medium bombers but was a broadly based force intended to support national strategy and could carry out operational, tactical and strategic bombing operations. While Allied air forces in 1940 were tied to the support of the army, the Luftwaffe deployed its resources in a more general, operational way. It switched from air superiority missions, to medium-range interdiction, to strategic bombing, to close air support duties depending on the need of the ground forces. It was not a Panzer spearhead arm, since in 1939 fewer than 15 percent of Luftwaffe aircraft were designed for close support as this was not its main role.
It is generally supposed that the Germans also had a major advantage in anti-aircraft guns, or Flak. In reality, the generally cited figure of 2,600 88 mm (3.46 in) heavy Flak guns and 6,700 37 mm (1.46 in) and 20 mm (0.79 in) light Flak seems to refer to the German armed forces total inventory, including the anti-aircraft defences of Germany's cities and ports and the equipment of training units. (A 9,300-gun Flak component with the field army would have involved more troops than the entire British Expeditionary Force.) The actual provision of Flak for the invading forces was 85 heavy and 18 light batteries belonging to the Luftwaffe, 48 "companies" of light Flak integral to divisions of the army, and 20 "companies" of light Flak allocated as army troops, that is, as a disposable reserve in the hands of HQs above corps level: altogether about 700 88 mm (3.46 in) and 180 37 mm (1.46 in) guns manned by Luftwaffe ground units and 816 20 mm (0.79 in) guns manned by the army.
France had spent a higher percentage of its GNP from 1918 to 1935 on its military than other great powers and the government had added a large rearmament effort in 1936. A declining birthrate during the period of the First World War and Great Depression and the large number of men who died in World War I, led to the hollow years, when France would have a shortage of men relative to its population, which was barely half that of Germany. France mobilised about one-third of the male population between the ages of 20 and 45, bringing the strength of its armed forces to 5,000,000. Only 2,240,000 of these served in army units in the north. The British contributed a total strength of 897,000 men in 1939, rising to 1,650,000 by June 1940. In May, it numbered only 500,000 men, including reserves. Dutch and Belgian manpower reserves amounted to 400,000 and 650,000, respectively.
The French raised 117 divisions, of which 104 (including 11 in reserve) were for the defence of the north. The British contributed 13 divisions in the BEF, three of which were untrained and poorly-armed labour divisions. Twenty-two Belgian, ten Dutch and two Polish divisions were also part of the Allied order of battle. British artillery strength amounted to 1,280 guns, Belgium fielded 1,338 guns, the Dutch 656 guns and France 10,700 guns, giving an Allied total of about 14,000 guns, 45 percent more than the German total. The French army was also more motorised than its opponent, which still relied on horses. Although the Belgians, British and Dutch had few tanks, the French had 3,254 tanks, larger than the German tank fleet.
The French Army was of mixed quality. It had in its order of battle some formidable units. The light and heavy armoured divisions (DLM and DCR) were new and not thoroughly trained. B Divisions were composed of reservists, above 30 years old and ill-equipped. A serious qualitative deficiency was a lack of anti-aircraft artillery, mobile anti-tank artillery and radio communication systems, despite the efforts of Gamelin to produce mobile artillery units. Only 0.15 percent of military spending between 1923 and 1939 had been on radios and other communications equipment; to maintain signals security, Gamelin used telephones and couriers to communicate with field units.
French tactical deployment and the use of mobile units at the operational level of war was also inferior to that of the Germans. The French had 3,254 tanks on the north-eastern front on 10 May, against 2,439 German tanks. Much of the armour was distributed for infantry support, each army having been assigned a tank brigade (groupement) of about ninety light infantry tanks but with so many tanks available the French could still concentrate a considerable number of light, medium and heavy tanks in armoured divisions, which in theory were as powerful as German panzer divisions. Only heavy French tanks generally carried wireless and the ones fitted were unreliable, which hampered communication and made tactical manoeuvre more difficult compared to German units. In 1940, French military theorists still mainly considered tanks as infantry support vehicles and French tanks were slow (except for the SOMUA S35) compared to German tanks, enabling German tanks to offset their disadvantages by out-manoeuvring French tanks. At various points in the campaign, the French were not able to achieve the same tempo as German armoured units. The state of training was also unbalanced, with the majority of personnel trained only to man static fortifications. Minimal training for mobile action was carried out between September 1939 and May 1940.
The French army was composed of three Army Groups. The 2nd and 3rd Army Groups defended the Maginot Line to the east; the 1st Army Group under Gaston Billotte was situated in the west and would execute the movement forward into the Low Countries. Initially positioned on the left flank near the coast, the Seventh Army, reinforced by a Divisions Légères Méchanique (DLM), was intended to move to the Netherlands via Antwerp. Next to the south were the motorised divisions of the BEF, which would advance to the Dyle Line and position itself to the right of the Belgian army, from Leuven (Louvain) to Wavre. The First Army, reinforced by two light mechanised divisions and with a Division Cuirassée de Réserve (DCR, Reserve Armoured Division) in reserve, would defend the Gembloux Gap between Wavre and Namur. The southernmost army involved in the move forward into Belgium was the French Ninth Army, which had to cover the Meuse sector between Namur to the north of Sedan.
Lord Gort, commander of the BEF, expected that he would have two or three weeks to prepare for the Germans to advance 100 kilometres (62 mi) to the Dyle but the Germans arrived in four days. The Second Army was expected to form the "hinge" of the movement and remain entrenched. It was to face the elite German armoured divisions in their attack at Sedan. It was given low priority for manpower, anti-aircraft and anti-tank weapons and air support, consisting of five divisions, two were over-age reservist "Serie B" divisions and the 3rd North African Division. Considering their training and equipment, they had to cover a long front and formed a weak point of the French defence system. This stemmed from the French High Command's belief that the Ardennes forest was impassable to tanks, even though intelligence from the Belgian army and from their own intelligence services warned them of long armour and transport columns crossing the Ardennes and being stuck in a huge traffic-jam for some time. French war games in 1937 and 1938 had shown that the Germans could penetrate the Ardennes and André Corap the Ninth Army commander called it "idiocy" to think that the enemy could not get through. General Gamelin ignored the evidence, as it was not in line with his strategy.
In the air, the Allies were outnumbered. The Armée de l'Air had 1,562 aircraft, and RAF Fighter Command committed 680 machines, while RAF Bomber Command could contribute some 392 aircraft to operations. Some of the Allied types were approaching obsolescence, such as the Fairey Battle. In the fighter force, only the British Hawker Hurricane and the French Dewoitine D.520 could contend with the German Messerschmitt Bf 109, the D.520 having better manoeuvrability although being slightly slower. On 10 May 1940, only 36 D.520s had been dispatched, all to one squadron. In fighter aircraft, the Allies had the numerical advantage; 836 German Bf 109s against 81 Belgian, 261 British and 764 French fighters of various types. The French and British also had larger aircraft reserves.
In early June 1940, the French aviation industry had reached a considerable output, with an estimated reserve of nearly 2,000 aircraft. A chronic lack of spare parts crippled this fleet. Only 29 percent (599) of the aircraft were serviceable, of which 170 were bombers. Low serviceability meant the Germans had a clear numerical superiority in medium bomber aircraft, with six times as many as the French. Despite its disadvantages the Armée de l'Air performed far better than expected, destroying 916 enemy aircraft in air-to-air combat during the Battle of France, for a kill ratio of 2.35:1, with almost a third of those kills accomplished by French pilots flying the US built Curtiss Hawk 75, which accounted for 12.6 percent of the French single-seat fighter force.
In addition to 580 13 mm (0.5 in) machine guns assigned to civilian defence, the French Army had 1,152 25 mm (0.98 in) anti-aircraft guns, with 200 20 mm (0.79 in) auto-cannons in the process of delivery and 688 75 mm (2.95 in) guns and 24 90 mm (3.54 in) guns, the latter having problems with barrel wear. There were also 40 First World War-vintage 105 mm (4.1 in) anti-aircraft guns available. The BEF had 10 regiments of QF 3.7-inch heavy anti-aircraft guns, the most advanced in the world and 7 1⁄2 regiments of Bofors 40 mm light anti-aircraft guns, about 300 heavy and 350 light anti-aircraft guns. The Belgians had two heavy anti-aircraft regiments and were introducing Bofors 40 mm light anti-aircraft guns for divisional anti-aircraft troops. The Dutch had 84 75 mm (2.95 in), 39 elderly 60 mm (2.36 in), seven 100 mm (3.9 in), 232 20 mm (0.79 in) 40 mm (1.57 in) anti-aircraft guns and several hundred First World War-vintage Spandau M.25 machine guns on anti-aircraft mountings.
Fall Gelb began on the evening of 9 May, when German forces occupied Luxembourg virtually unopposed. Army Group B launched its feint offensive during the night into the Netherlands and Belgium and on the morning of 10 May, Fallschirmjäger (paratroopers) from the 7th Flieger Division and 22nd Luftlande Division (Kurt Student) executed surprise landings at The Hague, on the road to Rotterdam and against the Belgian Fort Eben-Emael to facilitate Army Group B's advance. The French command reacted immediately, sending the 1st Army Group north in accordance with Plan D. This move committed their best forces, diminishing their fighting power by the partial disorganisation it caused and their mobility by depleting their fuel stocks. By the time the French Seventh Army crossed the Dutch border, they found the Dutch already in full retreat and withdrew into Belgium to protect Antwerp.
The Luftwaffe was guaranteed air superiority over the Netherlands by greater numbers; 247 medium bombers, 147 fighters, 424 Junkers Ju 52 transports, and 12 Heinkel He 59 seaplanes being involved in operations over the Netherlands. The Dutch Air Force, (Militaire Luchtvaartafdeling, ML), had a strength of 144 combat aircraft, half of which were destroyed on the first day. The remainder of the ML was dispersed and accounted for only a handful of Luftwaffe aircraft shot down. In total the ML flew a mere 332 sorties, losing 110 aircraft.
The German 18th Army secured all the strategically vital bridges during the Battle of Rotterdam, which penetrated Fortress Holland and bypassed the New Water Line from the south. An operation organised separately by the Luftwaffe, the Battle for The Hague, failed. The airfields surrounding the city (Ypenburg, Ockenburg and Valkenburg) were captured in a costly victory, with many transport aircraft lost and the Dutch army re-captured the airfields by the end of the day. Some 96 aircraft in all were lost to Dutch shell fire. The Luftwaffe's Transportgruppen operations had cost 125 Ju 52s destroyed and 47 damaged, representing 50 percent of the fleet's strength. The airborne operation had cost the German paratroopers 4,000 men, of whom 1,200 were prisoners of war, out of 8,000, that were evacuated to Britain, a loss of 20 percent of NCOs and men and 42 percent of their officers.
The French Seventh Army failed to block the German armoured reinforcements from the 9th Panzer Division, which reached Rotterdam on 13 May. That same day in the east, following the Battle of the Grebbeberg, in which a Dutch counter-offensive to contain a German breach failed, the Dutch retreated from the Grebbe line to the New Water Line. The Dutch Army, still largely intact, surrendered in the evening of 14 May after the Bombing of Rotterdam by the Luftwaffe. Heinkel He 111 medium bombers of Kampfgeschwader 54 (Bomber Wing 54) destroyed the centre of the city, an act which has remained controversial. The Dutch Army considered its strategic situation to have become hopeless and feared further destruction of Dutch cities. The capitulation document was signed on 15 May. Dutch forces continued fighting in the Battle of Zeeland (where the French army had entered) and in the colonies while Queen Wilhelmina established a government in exile in Britain. Dutch casualties amounted to 2,157 army, 75 air force and 125 Navy personnel; 2,559 civilians were also killed.
The Germans were able to establish air superiority in Belgium. Having completed thorough photographic reconnaissance, they destroyed 83 of the 179 aircraft of the Aeronautique Militaire within the first 24 hours of the invasion. The Belgians flew 77 operational missions but this contributed little to the air campaign. As a result, the Luftwaffe was assured air superiority over the Low Countries. Because Army Group B's composition had been so weakened compared to the earlier plans, the feint offensive by the 6th Army was in danger of stalling immediately, since the Belgian defences on the Albert Canal position were very strong. The main approach route was blocked by Fort Eben-Emael, a large fortress then generally considered the most modern in Europe, which controlled the junction of the Meuse and the Albert Canal.
Delay might endanger the outcome of the entire campaign, because it was essential that the main body of Allied troops be engaged before Army Group A established bridgeheads. To overcome this difficulty, the Germans resorted to unconventional means in the Battle of Fort Eben-Emael. In the early hours of 10 May, DFS 230 gliders landed on top of the fort and unloaded assault teams that disabled the main gun cupolas with hollow charges. The bridges over the canal were seized by German paratroopers. The Belgians launched considerable counterattacks which were broken up by the Luftwaffe. Shocked by a breach in its defences just where they had seemed the strongest, the Belgian Supreme Command withdrew its divisions to the KW-line five days earlier than planned. Similar operations against the bridges in the Netherlands, at Maastricht, failed. All were blown up by the Dutch and only one railway bridge was taken. This stalled the German armour on Dutch territory for a time.
The BEF and the French First Army were not yet entrenched, and the news of the defeat on the Belgian border was unwelcome. The Allies had been convinced Belgian resistance would have given them several weeks to prepare a defensive line at the Gembloux Gap. When General Erich Hoepner's XVI Panzerkorps, consisting of 3rd Panzer Division and 4th Panzer Division, was launched over the newly captured bridges in the direction of the Gembloux Gap, this seemed to confirm the expectations of the French Supreme Command that the German central point of attack would be at that point. Gembloux was located between Wavre and Namur, on flat, ideal tank terrain. It was also an unfortified part of the Allied line. To gain time to dig in there, René Prioux, commanding the Cavalry Corps of the French First Army, sent the 2nd DLM and 3rd DLM towards the German armour at Hannut, east of Gembloux. They would provide a screen to delay the Germans and allow sufficient time for the First Army to dig in.
The Battle of Hannut, from 12–13 May, was the largest tank battle yet fought, with about 1,500 armoured fighting vehicles involved. The French disabled about 160 German tanks for 91 Hotchkiss H35 and 30 Somua S35 tanks destroyed or captured. (The Germans controlled the battlefield after a French withdrawal and recovered many of their knocked-out tanks, the German net loss amounting to 20 tanks of the 3rd Panzer Division and 29 of the 4th Panzer Division). Prioux had achieved his mission in stalling the Panzers and allowing the First Army to settle, was a strategic victory for the French. Hoepner had succeeded in diverting the First Army from Sedan, which was his most important mission but failed to destroy or forestall it. The French escaped encirclement and gave invaluable support to the BEF in Dunkirk two weeks later. On 14 May, having been stalled at Hannut, Hoepner tried to break the French line again, against orders, leading to The Battle of the Gembloux Gap. This was the only time in the campaign when German armour frontally attacked a strongly held fortified position. The attempt was repelled by the 1st Moroccan Infantry Division, costing the 4th Panzer Division another 42 tanks, 26 of which were irreparable but the French defensive success was made irrelevant by events further south.
In the centre, the progress of German Army Group A was to be delayed by Belgian motorised infantry and French mechanised cavalry divisions (DLC, Divisions Légères de Cavalerie) advancing into the Ardennes. The main resistance came from the Belgian 1st Chasseurs Ardennais along with the 5e Division Légère de Cavalerie (5th DLC). These forces had insufficient anti-tank capacity to block the surprisingly large number of German tanks they encountered and quickly gave way, withdrawing behind the Meuse. The German advance was greatly hampered by the sheer number of troops trying to force their way along the poor road network. Kleist's Panzergruppe had more than 41,000 vehicles. This huge armada had been allocated only four march routes through the Ardennes. The time-tables proved to be wildly optimistic and there was soon heavy congestion, beginning well over the Rhine to the east, which would last for almost two weeks. This made Army Group A very vulnerable to French air attacks, but these did not materialise. Although Gamelin was well aware of the situation, the French bomber force was far too weak to challenge German air superiority so close to the German border. The French had tried in vain to stem the flow of the German armour during the Battle of Maastricht and had failed with heavy losses. In two days, the bomber force had been reduced from 135 to 72.
On 11 May, Gamelin had ordered reserve divisions to begin reinforcing the Meuse sector. Because of the danger the Luftwaffe posed, movement over the rail network was limited to night-time, slowing the reinforcement, but the French felt no sense of urgency as they believed the build-up of German divisions would be correspondingly slow. The French Army did not conduct river crossings unless assured of heavy artillery support. While they were aware that the German tank and infantry formations were strong, they were confident in their strong fortifications and artillery superiority. However, the capabilities of the French units in the area were dubious; in particular, their artillery was designed for fighting infantry, and they were short of both antiaircraft and antitank guns. The German advance forces reached the Meuse line late in the afternoon of 12 May. To allow each of the three armies of Army Group A to cross, three major bridgeheads were to be established: at Sedan in the south, Monthermé to the north-west and Dinant further to the north. The first German units to arrive hardly had local numerical superiority; their already insufficient artillery support was further limited by an average supply of just 12 rounds per gun. Fortunately for the German divisions, the French artillery was also rationed to 30 rounds per gun per day.
At Sedan, the Meuse Line consisted of a strong defensive belt 6 km (3.7 mi) deep, laid out according to the modern principles of zone defence on slopes overlooking the Meuse valley and strengthened by 103 pillboxes, manned by the 147th Fortress Infantry Regiment. Deeper positions were held by the 55th Infantry Division, a grade "B" reserve division. On the morning of 13 May, the 71st Infantry Division was inserted to the east of Sedan, allowing 55th Infantry to narrow its front by one-third and deepen its position to over 10 km (6.2 mi). The division had a superiority in artillery to the German units present. On 13 May, the German XIX Korps forced three crossings near Sedan, executed by the 1st Panzer Division, 2nd Panzer Division and 10th Panzer Division, reinforced by the elite Infantry Regiment Großdeutschland. Instead of slowly massing artillery as the French expected, the Germans concentrated most of their air power (as they lacked strong artillery forces), to smash a hole in a narrow sector of the French lines by carpet bombing and by dive bombing. Guderian had been promised extraordinarily heavy air support during a continual eight-hour air attack, from 08:00 am until dusk.
The Luftwaffe executed the heaviest air bombardment the world had yet witnessed and the most intense by the Germans during the war. The Luftwaffe committed two Sturzkampfgeschwader (dive bomber wings) to the assault, flying 300 sorties against French positions. A total of 3,940 sorties were flown by nine Kampfgeschwader (Bomber Wings). Some of the forward pillboxes were unaffected and repulsed the crossing attempts of the 2nd Panzer Division and 10th Panzer Division. The morale of the deeper units of the 55th Infantry, however, had been broken by the effect of the air attacks. The French supporting artillery batteries had fled. The German infantry, at a cost of a few hundred casualties, had penetrated up to 8 km (5.0 mi) into the French defensive zone by midnight. Even by then most of the infantry had not crossed, much of the success being due to the actions of just six platoons, mainly assault engineers.
The disorder that had begun at Sedan spread down the French lines. At 19:00 on 13 May, the 295th regiment of 55th Infantry Division, holding the last prepared defensive line at the Bulson ridge 10 km (6.2 mi) behind the river, was panicked by alarmist rumours that German tanks were already behind its positions. It fled, creating a gap in the French defences, before even a single German tank had crossed the river. This "Panic of Bulson" also involved the divisional artillery. The Germans had not attacked their position, and would not do so until 12 hours later, at 07:20 on 14 May. Recognising the gravity of the defeat at Sedan, General Gaston-Henri Billotte, commander of the 1st Army Group, whose right flank pivoted on Sedan, urged that the bridges across the Meuse be destroyed by air attack, convinced that "over them will pass either victory or defeat!". That day, every available Allied light bomber was employed in an attempt to destroy the three bridges, but failed to hit them while suffering heavy losses. Some 44 percent of the Allies' bomber strength was destroyed.
Guderian had indicated on 12 May that he wanted to enlarge the bridgehead to at least 20 km (12 mi). His superior, General Ewald von Kleist, ordered him, on behalf of Hitler, to limit his moves to a maximum of 8 km (5.0 mi) before consolidation. At 11:45 on 14 May, Rundstedt confirmed this order, which implied that the tank units should now start to dig in. Guderian was able to get Kleist to agree to "reconnaissance in force", by threatening to resign and behind-the-scenes interventions. This vague terminology allowed Guderian to move forward, effectively ignoring Ewald von Kleist's order to halt. In the original Manstein Plan, as Guderian had suggested, secondary attacks would be carried out to the southeast, in the rear of the Maginot Line, to confuse the French command. This element had been removed by Halder but Guderian now sent the 10th Panzer Division and Großdeutschland infantry regiment south to execute precisely such a feint attack, using the only available route south over the Stonne plateau.
The commander of the French Second Army, General Charles Huntziger, intended to carry out a counter-attack at the same spot by the armoured 3e Division Cuirassée (3e DCR) to eliminate the bridgehead. This resulted in an armoured collision, both parties trying in vain to gain ground in furious attacks from 15–17 May, the village of Stonne changing hands many times. Huntzinger considered this at least a defensive success and limited his efforts to protecting his flank. Holding Stonne and taking Bulson would have enabled the French to hold onto the high ground overlooking Sedan. They could disrupt the Sedan bridgehead, even if they could not take it. Heavy battles took place and Stonne changed hands 17 times. It fell to the Germans for the last time on the evening of 17 May. Guderian turned the 1st Panzer Division and the 2nd Panzer Division westwards on 14 May, which advanced swiftly down the Somme valley towards the English Channel.
On 15 May, in heavy fighting, Guderian's motorised infantry dispersed the reinforcements of the new French Sixth Army in their assembly area west of Sedan, undercutting the southern flank of the French Ninth Army. The Ninth Army collapsed and surrendered en masse. The 102nd Fortress Division, its flanks unsupported, was surrounded and destroyed on 15 May at the Monthermé bridgehead by the 6th Panzer Division and 8th Panzer Division acting without air support. The French Second Army had also been seriously mauled and rendered impotent, and the Ninth Army was giving way because they did not have time to fortify their lines. Erwin Rommel had breached its defences within 24 hours of its conception. This allowed Rommel to break free with his 7th Panzer Division, refusing to allow his division rest and advancing both by day and night. The Ghost division advanced 30 mi (48 km) in just 24 hours.
Rommel's lines of communication with his superior, General Hermann Hoth, and his headquarters were cut. Disobeying orders and not waiting for the French to establish a new line of defence, he continued to advance north-west to Avesnes-sur-Helpe, just ahead of the 1st and 2nd Panzer divisions. The 5th Motorised Infantry Division had set up its overnight bivouac directly in Rommel's path, leaving its vehicles neatly lined up along the roadsides. Rommel's tanks dashed right through them. The slow speed, overloaded crews and lack of any means of communication in battle undid the French. The 5th Panzer Division joined in the fight. The French did inflict significant losses on the division but they could not cope with the speed of the German mobile units, which closed fast and destroyed the French armour at close range. During this battle, the remaining elements of the 1st DCR, resting after losing all but 16 of its tanks in Belgium, were also engaged and defeated. The French unit retreated, with just three remaining tanks. The 1st DCR was effectively destroyed on 17 May. The Germans lost 50 out of 500 tanks in the battle.
By 17 May, Rommel claimed to have taken 10,000 prisoners and suffered only 36 losses. Guderian was delighted with the fast advance, and encouraged XIX Korps to head for the channel, continuing until fuel was exhausted. However, the success of his commanders on the ground began to have effects on Hitler, who worried that the German advance was moving too fast. Halder recorded in his diary on 17 May that "Führer is terribly nervous. Frightened by his own success, he is afraid to take any chance and so would pull the reins on us ... [he] keeps worrying about the south flank. He rages and screams that we are on the way to ruin the whole campaign." Through deception and different interpretations of orders to stop from Hitler and von Kleist, the commanders on the ground were able to ignore Hitler's attempts to stop the northern advance to the sea.
The French High Command, already contemplatively ponderous and sluggish via its firm espousal of the broad strategy of "methodological warfare", however, was reeling from the shock of the sudden offensive and was now stung by a sense of defeatism. On the morning of 15 May, French Prime Minister Paul Reynaud telephoned the new British Prime Minister, Winston Churchill and said "We have been defeated. We are beaten; we have lost the battle." Churchill, attempting to offer some comfort to Reynaud, reminded the Prime Minister of all the times the Germans had broken through the Allied lines in the First World War only to be stopped. Reynaud was, however, inconsolable.
Churchill flew to Paris on 16 May. He immediately recognised the gravity of the situation when he observed that the French government was already burning its archives and was preparing for an evacuation of the capital. In a sombre meeting with the French commanders, Churchill asked General Gamelin, "Où est la masse de manoeuvre?" ["Where is the strategic reserve?"] that had saved Paris in the First World War. "Aucune" ["There is none"] Gamelin replied. After the war, Gamelin claimed his response was "There is no longer any." Churchill later described hearing this as the single most shocking moment in his life. Churchill asked Gamelin where and when the general proposed to launch a counterattack against the flanks of the German bulge. Gamelin simply replied "inferiority of numbers, inferiority of equipment, inferiority of methods".
Some of the best Allied units in the north had seen little fighting. Had they been kept in reserve they might have been used in a decisive counter-strike. In a twist of irony, pre-war General Staff Studies had asserted the main reserves were to be kept on French soil to resist an invasion of the Low Countries and deliver a counterattack or "re-establish the integrity of the original front". Despite having a numerically superior armoured force, the French failed to use it properly, or to deliver an attack on the vulnerable German bulge. The Germans combined their fighting vehicles in major, operational formations and used them at the point of main effort. The bulk of French armour was scattered along the front in tiny formations. Most of the French reserve divisions had by now been committed. The 1st DCR had been wiped out when it had run out of fuel and the 3rd DCR had failed to take its opportunity to destroy the German bridgeheads at Sedan. The only armoured division still in reserve, 2nd DCR, was to attack on 16 May west of Saint-Quentin, Aisne. The division's commander could locate only seven of its 12 companies, which were scattered along a 49 mi × 37 mi (79 km × 60 km) front. The formation was overrun by the 8th Panzer Division while still forming up and was effectively destroyed as a fighting unit.
The 4th DCr (de Gaulle), attempted to launch an attack from the south at Montcornet, where Guderian had his Korps headquarters and the 1st Panzer Division had its rear service areas. During the Battle of Montcornet Germans hastily improvised a defence while Guderian rushed up the 10th Panzer Division to threaten De Gaulle's flank. This flank pressure and dive-bombing by Fliegerkorps VIII (General Wolfram von Richthofen) broke up the attack. French losses on 17 May amounted to 32 tanks and armoured vehicles but the French had "inflicted loss on the Germans". On 19 May, after receiving reinforcements, de Gaulle attacked again and was repulsed with the loss of 80 of 155 vehicles. Fliegerkorps VIII attacked French units massing on the German flanks and prevented most counter-attacks from starting. The defeat of the 4th DCr and the disintegration of the French Ninth Army was caused mainly by the fliegerkorps. The 4th DCr had achieved a measure of success but the attacks on 17 and 19 May had only local effect.
On 19 May, General Edmund Ironside, the British Chief of the Imperial General Staff (CIGS), conferred with General Lord Gort, commander of the BEF, at his headquarters near Lens. He urged Gort to save the BEF by attacking south-west toward Amiens. Gort replied that seven of his nine divisions were already engaged on the Scheldt River and he had only two divisions left to mount such an attack. Ironside then asked Gort under whose command he was acting. Gort replied that this was General Billotte, the commander of the French 1st Army Group but that Billotte had issued no orders for eight days. Ironside confronted Billotte, whose own headquarters was nearby and found him apparently incapable of taking action. He returned to Britain concerned that the BEF was doomed and ordered urgent anti-invasion measures.
The German land forces could not remain inactive any longer, since it would allow the Allies to reorganise their defence or escape. On 19 May, Guderian was permitted to start moving again and smashed through the weak 12th (Eastern) Division and the 23rd (Northumbrian) Division (Territorial divisions) on the Somme river. The German units occupied Amiens and secured the westernmost bridge over the river at Abbeville. This move isolated the British, French, Dutch and Belgian forces in the north from their supplies. On 20 May, a reconnaissance unit from the 2nd Panzer Division reached Noyelles-sur-Mer, 100 kilometres (62 mi) to the west of their positions on 17 May. From Noyelles, they were able to see the Somme estuary and the English Channel. A huge pocket, containing the Allied 1st Army Group (the Belgian, British, and French First, Seventh and Ninth armies), was created.
Fliegerkorps VIII covered the dash to the channel coast. Heralded as the finest hour of the Ju 87 (Stuka), these units responded via an extremely efficient communications system to requests for support, which blasted a path for the army. The Ju 87s were particularly effective at breaking up attacks along the flanks of the German forces, breaking fortified positions and disrupting supply routes. Radio-equipped forward liaison officers could call upon the Stukas and direct them to attack Allied positions along the axis of advance. In some cases, the Luftwaffe responded to requests within 10 to 20 minutes. Oberstleutnant Hans Seidemann the Fliegerkorps vIII Chief of Staff, said that "never again was such a smoothly functioning system for discussing and planning joint operations achieved". Closer examination reveals the army had to wait 45–75 minutes for Ju 87 units and ten minutes for Henschel Hs 123s.
On the morning of 20 May, Gamelin ordered the armies trapped in Belgium and northern France to fight their way south and link up with French forces attacking northwards from the Somme river. On the evening of 19 May, the French Prime Minister, Paul Reynaud had sacked Gamelin and replaced him with Maxime Weygand, who claimed his first mission as Commander-in-Chief would be to get a good night's sleep. Gamelin's orders were cancelled and Weygand took several days during the crisis, to make courtesy visits in Paris. Weygand proposed a counter-offensive by the armies trapped in the north combined with an attack by French forces on the Somme front, the new French 3rd Army Group (General Antoine-Marie-Benoît Besson).
The corridor through which Panzergruppe von Kleist had advanced to the coast was narrow and to the north were the three DLMs and the BEF; to the south was the 4th DCR. Allied delays caused by the French change of command gave the German infantry divisions time to follow up and reinforce the panzer corridor and the tanks had pushed further along the channel coast. Weygand flew into the pocket on 21 May and met Billotte, the commander of the 1st Army Group and King Leopold III of Belgium. Leopold announced that the Belgian Army could not conduct offensive operations as it lacked tanks and aircraft and that unoccupied Belgium had enough food for only two weeks. Leopold did not expect the BEF to endanger itself to keep contact with the Belgian Army but warned that if it persisted with the southern offensive, the Belgian army would collapse. Leopold suggested the establishment of a beach-head covering Dunkirk and the Belgian channel ports.
Gort doubted that the French could prevail and on 23 May, Billotte, the only Allied commander in the north briefed on the Weygand plan, was killed in a road accident, leaving the 1st Army Group leaderless for three days. That day, the British decided to evacuate from the Channel ports. Only two local offensives, by the British and French in the north at Arras on 21 May and by the French from Cambrai in the south on 22 May, took place. Frankforce (Major-General Harold Franklyn) consisting of two divisions, had moved into the Arras area but Franklyn was not aware of a French push north toward Cambrai and the French were ignorant of a British attack towards Arras. Franklyn assumed he was to relieve the Allied garrison at Arras and to cut German communications in the vicinity and was reluctant to commit the 5th Infantry Division, 50th (Northumbrian) Infantry Division, with the 3rd DLM from the French First Army providing flank protection, in a limited objective attack. Only two British infantry battalions and two Army Tank battalions with 74 Matilda II tanks and 14 light tanks took part in the main attack.
The Battle of Arras achieved surprise and initial success against overstretched German forces but failed in its objective. Radio communication between tanks and infantry was poor and there was little combined arms co-ordination as practised by the Germans. German defences (including 88 mm (3.46 in) FlaK guns and 105 mm (4.1 in) field guns) eventually stopped the attack. The French knocked out many German tanks as they retired but the Luftwaffe broke up the counter-attacks and 60 British tanks were lost. The southern attack at Cambrai also failed, because V Corps had been too disorganised after the fighting in Belgium to make a serious effort. OKH panicked at the thought of hundreds of Allied tanks smashing the best forces but Rommel wanted to continue the pursuit. Early on 22 May, OKH recovered and ordered the XIX Panzerkorps to press north from Abbeville to the Channel ports: the 1st Panzer Division to Calais, the 2nd Panzer Division to Boulogne and the 10th Panzer Division to Dunkirk (later, the 1st and 10th Panzer divisions roles were reversed. South of the German salient, limited French attacks near Peronne and Amiens on 23 May failed. French and British troops fought the Battle of Abbeville from 27 May to 4 June but failed to eliminate the German bridgehead south of the Somme.
In the early hours of 23 May, Gort ordered a retreat from Arras. By now, he had no faith in the Weygand plan, nor in Weygand's proposal at least to try to hold a pocket on the Flemish coast, a so-called Réduit de Flandres. Gort knew that the ports needed to supply such a foothold were already being threatened. That same day, the 2nd Panzer Division had assaulted Boulogne. The British garrison there surrendered on 25 May, although 4,286 men were evacuated by Royal Navy ships. The RAF also provided air cover, denying the Luftwaffe an opportunity to attack the shipping.
The 10th Panzer Division (Ferdinand Schaal), attacked Calais on 24 May. British reinforcements (the 3rd Royal Tank Regiment, equipped with cruiser tanks, and the 30th Motor Brigade) had been hastily landed 24 hours before the Germans attacked. The defenders held on to the port as long as possible, aware that an early capitulation would free up German forces to advance on Dunkirk. The British and French held the town despite the best efforts of Schaal's division to break through. Frustrated, Guderian ordered that if Calais had not fallen by 14:00 on 26 May, he would withdraw the 10th Panzer Division and ask the Luftwaffe to destroy the town. Eventually, the French and British ran out of ammunition and the Germans were able to break into the fortified city at around 13:30 on 26 May, 30 minutes before Schaal's deadline was up. Despite the French surrender of the main fortifications, the British held the docks until the morning of 27 May. Around 440 men were evacuated. The siege lasted for four crucial days. However, the delaying action came at a price. Some 60 percent of Allied personnel were killed or wounded.
Frieser wrote that the Franco-British counter-attack at Arras, had a disproportionate effect on the Germans because the German higher commanders were apprehensive about flank security. Kleist, the commander of Panzergruppe von Kleist perceived a "serious threat" and informed Halder that he had to wait until the crisis was resolved before continuing. Colonel-General Günther von Kluge, the 4th Army commander ordered the tanks to halt, with the support of Rundstedt. On 22 May, when the attack had been repulsed, Rundstedt ordered that the situation at Arras must be restored before Panzergruppe von Kleist moved on Boulogne and Calais. At OKW the panic was worse and Hitler contacted Army Group A on 22 May, to order that all mobile units were to operate either side of Arras and infantry units were to operate to the east.
The crisis among the higher staffs of the German army was not apparent at the front and Halder formed the same conclusion as Guderian, that the real threat was that the Allies would retreat to the channel coast too quickly and a race for the channel ports began. Guderian ordered the 2nd Panzer Division to capture Boulogne, the 1st Panzer Division to take Calais and the 10th Panzer division to seize Dunkirk. Most of the BEF and the French First Army were still 62 miles (100 km) from the coast but despite delays, British troops were sent from England to Boulogne and Calais just in time to forestall the XIX Corps panzer divisions on 22 May. Frieser wrote that had the panzers advanced at the same speed on 21 May as they had on 20 May, before the halt order stopped their advance for 24 hours, Boulogne and Calais would have fallen. (Without a halt at Montcornet on 15 May and the second halt on 21 May after the Battle of Arras, the final halt order of 24 May would have been irrelevant, because Dunkirk would have already been captured by the 10th Panzer Division.)
The British launched Operation Dynamo, which evacuated the encircled British, French and Belgian troops from the northern pocket in Belgium and Pas-de-Calais, beginning on 26 May. About 28,000 men were evacuated on the first day. The French First Army—the bulk of which remained in Lille—mounted a long defence of the city owing to Weygand's failure to pull it back along with other French forces to the coast. The 50,000 men involved finally capitulated on 31 May. While the First Army was mounting its sacrificial defence at Lille, it drew German forces away from Dunkirk, allowing 70,000 Allied soldiers to escape. Total Allied evacuation rates stood at 165,000 on 31 May. The Allied position was complicated by Belgian King Leopold III's surrender on 27 May, which was postponed until 28 May. The gap left by the Belgian Army stretched from Ypres to Dixmude. Nevertheless, a collapse was prevented and 139,732 British and 139,097 French soldiers were evacuated. Between 31 May and 4 June, some 20,000 British and 98,000 French were saved. Still, some 30–40,000 French soldiers of the rearguard remained to be captured. The overall total evacuated was 338,226, including 215,000 British.
During the Dunkirk battle, the Luftwaffe did its best to prevent the evacuation. It flew 1,882 bombing and 1,997 fighter sorties. British losses totalled 6 percent of their total losses during the French campaign, including 60 precious fighter pilots. The Luftwaffe failed in its task of preventing the evacuation, but inflicted serious losses on the Allied forces. A total of 89 merchantmen (of 126,518 grt) were lost; the navy lost 29 of its 40 destroyers sunk or seriously damaged. The Germans lost around 100 aircraft confirmed destroyed, and the RAF 106 fighters. Other sources put Luftwaffe losses in the Dunkirk area at 240.
Confusion still reigned. After the evacuation at Dunkirk and while Paris was enduring a short-lived siege, part of the 1st Canadian Infantry Division was sent to Brittany, but was withdrawn after the French capitulation. The British 1st Armoured Division under General Evans, without its infantry which had earlier been diverted to the defence of Calais, arrived in France in June 1940. It was joined by the former labour battalion of the 51st (Highland) Division and was forced to fight a rearguard action. At the end of the campaign, Erwin Rommel praised the staunch resistance of British forces, despite being under-equipped and without ammunition for much of the fighting.
By the end of May 1940, the best and most modern French armies had been sent north and lost in the resulting encirclement; the French had also lost much of their heavy weaponry and their best armoured formations. Overall, the Allies had lost 61 divisions in Fall Gelb. Weygand was faced with the prospect of defending a long front (stretching from Sedan to the channel), with a greatly depleted French Army now lacking significant Allied support. Weygand had only 64 French divisions and the 51st (Highland) Infantry Division) available. Weygand lacked the reserves to counter a breakthrough or to replace frontline troops, should they become exhausted from a prolonged battle on a front of 965 km (600 mi). The Germans had 142 divisions to use and air supremacy except over the English Channel.
The French also had to deal with millions of civilian refugees fleeing the war in what became known as L'Exode (the Exodus); automobiles and horse-drawn carts carrying possessions clogged roads. As the government had not foreseen such a rapid military collapse, there were few plans to cope. Between six and ten million French fled, sometimes so quickly that they left uneaten meals on tables, even while officials stated that there was no need to panic and that civilians should stay. The population of Chartres declined from 23,000 to 800 and Lille from 200,000 to 20,000, while cities in the south such as Pau and Bordeaux rapidly grew in size.
Italy declared war on France and Britain on 10 June but Italy was not prepared for war and made little impact during the last two weeks of fighting in the Italian invasion of France. Italian dictator Benito Mussolini was aware of this and sought to profit from German successes. Mussolini felt the conflict would soon end and he reportedly said to the Army's Chief-of-Staff, Marshal Badoglio, "I only need a few thousand dead so that I can sit at the peace conference as a man who has fought". The Army of the Alps (General René Olry) defeated the Italian invasion.
The Germans renewed their offensive on 5 June on the Somme. During the next three weeks, far from the easy advance the Wehrmacht expected, they encountered strong resistance from a rejuvenated French Army. It had fallen back on its interior lines of supply and communications, and had closer access to repair shops, supply dumps and stores. Moreover, 112,000 evacuated French soldiers were repatriated via the Normandy and Brittany ports. It was some substitute for the lost divisions in Flanders. The French were also able to make good a significant amount of their armoured losses and raised the 1st and 2nd DCR (heavy armoured divisions). De Gaulle's division—the 4th DCR—also had its losses replaced. Morale rose and was very high by the end of May 1940. Most French soldiers that knew about the defeats, and were now joining the line, only knew of German success by hearsay.
Surviving French officers had increased tactical experience against German mobile units; increased confidence in their weapons after seeing their artillery, which the Wehrmacht post-battle analysis recognised as technically very good, and their tanks perform better in combat than the German armour. The French tanks were now known to have heavier armour and armament. Between 23 and 28 May, they reconstituted the French Seventh and Tenth armies. Weygand decided on hedgehog tactics, which were to implement defence in depth operations and use delaying tactics, to inflict maximum attrition on German units. He employed units in towns and small villages, as well as major towns and cities and fortified them 360° along their perimeter. Behind this, the new infantry, armoured and half-mechanised divisions formed up, ready to counter-attack and relieve the surrounded units, which were ordered to hold out at all costs.
Army Group B attacked either side of Paris. Of its 47 divisions it had the majority of the mobile units. In fact, after 48 hours into the offensive, the Germans had not made any major breakthroughs. The Germans had been "stopped in their tracks". On the Aisne, the XVI Panzerkorps employed over 1,000 AFVs, two Panzer divisions and a motorised division against the French. The assault was crude, and Hoepner soon lost 80 out of 500 AFVs in the first attack. The German 4th Army succeeded in capturing bridgeheads over the Somme river, but the Germans struggled to get over the Aisne. Weygand had organised a defence in depth and frustrated the crossing. At Amiens, the Germans were repeatedly driven back by powerful French artillery concentrations and came to recognise improved French tactics.
The German Army relied on the Luftwaffe to provide decisive assistance in silencing French guns, enabling the German infantry to inch forward. German progress was made only late on the third day of operations, finally forcing crossings; the French Air Force attempted to bomb them but failed. German sources acknowledged the battle was "hard and costly in lives, the enemy putting up severe resistance, particularly in the woods and tree lines continuing the fight when our troops had pushed passed the point of resistance". South of Abbeville, the French Tenth Army under General Robert Altmayer had its front broken and it was forced to retreat to Rouen and south along the Seine river. The rapid German advances were the sign of a weakening enemy. Rommel and his 7th Panzer Division headed west over the Seine river through Normandy and captured the port of Cherbourg on 18 June. On the way to Cherbourg, Rommel forced the surrender of the British 51st (Highland) Division on 12 June. In close-quarter combat, the Luftwaffe was struggling to have an impact. However, in an operational sense, they helped disperse French armour. The German spearheads were overextended and vulnerable to counter strokes, but the concentration of the Luftwaffe denied the French the ability to concentrate, and the fear of air attack negated their mass and mobile use by Weygand.
On 10 June, the French government declared Paris an open city. The German 18th Army now deployed against Paris. The French resisted the approaches to the capital strongly, but the line was broken in several places. Weygand now asserted it would not take long for the French Army to disintegrate. On 13 June, Churchill attended a meeting of the Anglo-French Supreme War Council at Tours. He suggested a Franco-British Union. It was rejected. On 14 June, Paris fell. Those Parisians who stayed in the city found that in most cases the Germans were extremely well mannered.
The situation in the air had also worsened, the Luftwaffe established air supremacy (as opposed to air superiority) as the French air arm was on the verge of collapse. The French Air Force (Armée de l'Air) had only just begun to make the majority of bomber sorties; between 5 and 9 June (during Operation Paula), over 1,815 missions, of which 518 were by bombers, were flown. The number of sorties flown declined as losses were now becoming impossible to replace. The RAF attempted to divert the attention of the Luftwaffe with 660 sorties flown against targets over the Dunkirk area, but losses were heavy; on 21 June alone, 37 Bristol Blenheims were destroyed. After 9 June, French aerial resistance virtually ceased; some surviving aircraft withdrew to French North Africa. The Luftwaffe now "ran riot". Its attacks were focused on the direct and indirect support of the German Army. The Luftwaffe subjected lines of resistance to ferocious assault, which then quickly collapsed under armoured attack.
Meanwhile, to the east, Army Group C was to help Army Group A encircle and capture the French forces on the Maginot line. The goal of the operation was to envelop the Metz region, with its fortifications, to prevent a French counteroffensive from the Alsace region against the German line on the Somme. Guderian's XIX Korps was to advance to the French border with Switzerland and trap the French forces in the Vosges Mountains while the XVI Korps attacked the Maginot Line from the west, into its vulnerable rear to take the cities of Verdun, Toul and Metz. The French, meanwhile, had moved the French 2nd Army Group from the Alsace and Lorraine to the 'Weygand line' on the Somme, leaving only small forces guarding the Maginot line. After Army Group B had begun its offensive against Paris and into Normandy, Army Group A began its advance into the rear of the Maginot line. On 15 June, Army Group C launched Operation Tiger, a frontal assault across the Rhine and into France.
German attempts to break open or into the Maginot line prior to Tiger had failed. One assault lasted for eight hours on the extreme north of the line, costing the Germans 46 dead and 251 wounded, while just two French were killed (one at Ferme-Chappy and one at Fermont fortress). On 15 June, the last well-equipped French forces, including the French Fourth Army, were preparing to leave as the Germans struck. The French now holding the line were skeletal. The Germans greatly outnumbered the French. They could call upon the I Armeekorps of seven divisions and 1,000 artillery pieces, although most were First World War vintage, and could not penetrate the thick armour of the fortresses. Only 88 mm guns could do the job, and 16 were allocated to the operation. To bolster this, 150 mm and eight railway batteries were also employed. The Luftwaffe deployed the Fliegerkorps V to give air support.
The battle was difficult and slow progress was made against strong French resistance. However, each fortress was overcome one by one. One fortress (Schoenenbourg) fired 15,802 75 mm rounds at attacking German infantry. It was the most heavily shelled of all the French positions. Nevertheless, its armour protected it from fatal damage. The same day Tiger was launched, Operation Kleiner Bär began. Five assault divisions of the VII Armeekorps crossed the Rhine into the Colmar area with a view to advancing to the Vosges Mountains. It had 400 artillery pieces bolstered by heavy artillery and mortars. They drove the French 104th Division and 105th Division back into the Vosges Mountains on 17 June. However, on the same day Guderian's XIX Korps reached the Swiss border and the Maginot defences were cut off from the rest of France. Most units surrendered on 25 June, and the Germans claimed to have taken 500,000 prisoners. Some main fortresses continued the fight, despite appeals for surrender. The last only capitulated on 10 July, after a request from Georges, and only then under protest. Of the 58 major fortifications on the Maginot Line, just 10 were captured by the Wehrmacht in battle.
The evacuation of the second BEF took place during Operation Ariel between 15 and 25 June. The Luftwaffe, with complete domination of the French skies, was determined to prevent more Allied evacuations after the Dunkirk debacle. I Fliegerkorps was assigned to the Normandy and Brittany sectors. On 9 and 10 June, the port of Cherbourg was subject to 15 tonnes of German bombs, while Le Havre received 10 bombing attacks that sank 2949 GRT of escaping Allied shipping. On 17 June, Junkers Ju 88s—mainly from Kampfgeschwader 30—sank a "10,000 tonne ship" which was the 16243 GRT liner RMS Lancastria off St Nazaire, killing some 4,000 Allied personnel (nearly doubling the British killed in the battle of France). Nevertheless, the Luftwaffe failed to prevent the evacuation of some 190,000–200,000 Allied personnel.
Discouraged by his cabinet's hostile reaction to a British proposal to unite France and Britain to avoid defeat, and believing that his ministers no longer supported him, Reynaud resigned on 16 June. He was succeeded by Marshal of France Philippe Pétain, who delivered a radio address to the French people announcing his intention to ask for an armistice with Germany. When Hitler received word from the French government that they wished to negotiate an armistice, he selected the Forest of Compiègne as the site for the negotiations.
Compiègne had been the site of the 1918 Armistice, which ended the First World War with a humiliating defeat for Germany; Hitler viewed the choice of location as a supreme moment of revenge for Germany over France. On 21 June 1940, Hitler visited the site to start the negotiations which took place in the very same railway carriage in which the 1918 Armistice was signed (it had just been removed from a museum building and placed on the precise spot where it was located in 1918). Hitler sat in the same chair in which Marshal Ferdinand Foch had sat when he faced the defeated German representatives. After listening to the reading of the preamble, Hitler left the carriage in a calculated gesture of disdain for the French delegates, and negotiations were turned over to Wilhelm Keitel, the Chief of Staff of OKW. The armistice was signed on the next day at 18:36 (French time), by General Keitel for Germany and Huntziger for France. The armistice and cease-fire went into effect, two days and six hours later, at 00:35 on 25 June, once the Franco-Italian Armistice had also been signed, at 18:35 on 24 June, near Rome.
In 2000, Ernest May wrote that Hitler had a better insight into the French and British governments than vice versa and knew that they would not go to war over Austria and Czechoslovakia, because he concentrated on politics rather than the state and national interest. From 1937 to 1940, Hitler stated his views on events, their importance and his intentions, then defended them against contrary opinion from the likes of former Chief of the General Staff Ludwig Beck and Weizsäcker. Hitler sometimes concealed aspects of his thinking but he was unusually frank about priority and his assumptions. May referred to Wheeler-Bennett (1964):
Except in cases where he had pledged his word, Hitler always meant what he said.
May asserted that in Paris, London and other capitals, there was an inability to believe that someone might want another world war. He wrote that, given public reluctance to contemplate another war and a need to reach consensus about Germany, the rulers of France and Britain were reticent (to take a stand against German aggression), which limited dissent at the cost of enabling assumptions that suited their convenience. In France, Édouard Daladier withheld information until the last moment, and then presented the Munich Agreement to the French cabinet as a fait accompli in September 1938, thus avoiding discussions over whether Britain would follow France into war or if the military balance was really in Germany's favour or how significant it was. The decision for war in September 1939 and the plan devised in the winter of 1939–1940 by Daladier for war with the USSR followed the same pattern.
Hitler miscalculated Franco-British reactions to the invasion of Poland in September 1939, because he had not realised that a shift in public opinion had occurred in mid-1939. May asserted that the French and British could have defeated Germany in 1938 with Czechoslovakia as an ally and also in late 1939, when German forces in the West were incapable of preventing a French occupation of the Ruhr, which would have forced capitulation or a futile German resistance in a war of attrition. France did not invade Germany in 1939, because it wanted British lives to be at risk too and because of hopes that blockade might force a German surrender without a bloodbath. The French and British also believed that they were militarily superior and guaranteed victory. The run of victories enjoyed by Hitler from 1938–1940, could only be understood in the context of defeat being inconceivable to French and British leaders.
May wrote that when Hitler demanded a plan to invade France in September 1939, the German officer corps thought that it was foolhardy and discussed a coup d'état, only backing down when doubtful of the loyalty of the soldiers to them. With the deadline for the attack on France being postponed so often, OKH had time to revise Fall Gelb (Case Yellow) for an invasion over the Belgian Plain several times. In January 1940, Hitler came close to ordering the invasion but was prevented by bad weather. Until the Mechelen Incident in January forced a fundamental revision of Fall Gelb, the main effort (schwerpunkt) of the German army in Belgium would have been confronted by first-rate French and British forces, equipped with more and better tanks and with a great advantage in artillery. After the Mechelen Incident, OKH devised an alternative and hugely risky plan to make the invasion of Belgium a decoy, with the main effort switched to the Ardennes, to cross the Meuse and reach the Channel coast. May wrote that although the alternative plan was called the Manstein Plan, Guderian, Manstein, Rundstedt, Halder and Hitler had been equally important in its creation.
War games held by Generalmajor (Major-General) Kurt von Tippelskirch, the chief of army intelligence and Oberst Ulrich Liss of Fremde Heere West (FHW, Foreign Armies West), tested the concept of an offensive through the Ardennes. Liss thought that swift reactions could not be expected from the "systematic French or the ponderous English" and used French and British methods, which made no provision for surprise and reacted slowly, when one was sprung. The results of the war games persuaded Halder that the Ardennes scheme could work, even though he and many other commanders still expected it to fail. May wrote that without the reassurance of intelligence analysis and the results of the war games, the possibility of Germany adopting the last version of Fall Gelb would have been remote. The French Dyle-Breda variant of the Allied deployment plan was based on an accurate prediction of the German intentions, until the delays caused by the winter weather and shock of the Mechelen Incident led to the radical revision of Fall Gelb. The French sought to assure the British that they would act to prevent the Luftwaffe using bases in the Netherlands and the Meuse valley and to encourage the Belgian and Dutch governments. The politico-strategic aspects of the plan ossified French thinking and the Phoney War led to demands for Allied offensives in Scandinavia or the Balkans and the plan to start a war with the USSR. It was thought that changes to the Dyle-Breda variant might lead to forces being taken from the Western Front.
French and British intelligence sources were better than the German equivalents, which suffered from too many competing agencies, but intelligence analysis was not as well integrated into Allied planning and decision-making. Information was delivered to operations officers but there was no mechanism like the German practice of allowing intelligence officers to comment on planning assumptions about opponents and allies. The insularity of the French and British intelligence agencies meant that had they been asked if Germany would continue with a plan to attack across the Belgian plain after the Mechelen Incident, they would not have been able to point out how risky the Dyle-Breda variant was. May wrote that the wartime performance of the Allied intelligence services was abysmal. Daily and weekly evaluations had no analysis of fanciful predictions about German intentions and a May 1940 report from Switzerland, that the Germans would attack through the Ardennes, was marked as a German spoof. More items were obtained about invasions of Switzerland or the Balkans, while German behaviour consistent with an Ardennes attack, such as the dumping of supplies and communications equipment on the Luxembourg border and the concentration of Luftwaffe air reconnaissance around Sedan and Charleville-Mézières was overlooked.
According to May, French and British rulers were at fault for tolerating poor performance by the intelligence agencies and the fact that the Germans could achieve surprise in May 1940 showed that even with Hitler, the process of executive judgement in Germany had worked better than in France and Britain. May referred to Marc Bloch in Strange Defeat (1940), that the German victory was a "triumph of intellect", which depended on Hitler's "methodical opportunism". May further asserted that despite Allied mistakes, the Germans could not have succeeded but for outrageous good luck. German commanders wrote during the campaign and after that often only a small difference had separated success from failure. Prioux thought that a counter-offensive could still have worked up to 19 May but by then, Belgian refugees were crowded on the roads needed for redeployment and the French transport units, that had performed well in the advance into Belgium, failed for lack of plans to move them back. Gamelin had said "It is all a question of hours." but the decision to sack Gamelin and appoint Weygand, caused a delay of two days.
France was divided into a German occupation zone in the north and west and a "free zone" in the south. Both zones were nominally under the sovereignty of the French rump state headed by Pétain that replaced the French Third Republic; this rump state is often referred to as Vichy France. In response to the formation of a new political structure in France mandated by the Nazi government of Germany, De Gaulle, who had been made an Undersecretary of National Defence by Reynaud in London at the time of the armistice, delivered his Appeal of 18 June. With this speech, De Gaulle refused to recognise Pétain's Vichy government as legitimate and began the task of organising the Free French Forces.
The British doubted Admiral François Darlan's promise not to allow the French fleet at Toulon to fall into German hands by the wording of the armistice conditions. They feared the Germans would seize the French Navy's fleet, docked at ports in Vichy France and North Africa and use them in an invasion of Britain (Operation Sea Lion). Within a month, the Royal Navy attacked the French naval forces stationed in North Africa in the Attack on Mers-el-Kébir. The British Chiefs of Staff Committee had concluded in May 1940 that if France collapsed, "we do not think we could continue the war with any chance of success" without "full economic and financial support" from the United States. Churchill's desire for American aid led in September to the Destroyers for Bases agreement that began the wartime Anglo-American partnership.
The occupation of the various French zones continued until November 1942, when the Allies launched Operation Torch, the invasion of Western North Africa. To safeguard southern France, the Germans enacted Case Anton and occupied Vichy France. In June 1944, the Western Allies launched Operation Overlord, followed by the smaller but less opposed Operation Dragoon on the French Mediterranean coast on 15 August. This threatened to cut off German troops in western and central France, and most began to retire toward Germany. (The heavily fortified French Atlantic coast submarine bases remained stay-behind "fortresses" until the German capitulation.) On 24 August 1944 Paris was liberated, and by September 1944 most of the country was in Allied hands.
The Free French provisional government declared the re-establishment of a provisional French Republic to ensure continuity with the defunct Third Republic. It set about raising new troops to participate in the advance to the Rhine and the Western Allied invasion of Germany by using the French Forces of the Interior as military cadres and manpower pools of experienced fighters to allow a very large and rapid expansion of the French Liberation Army (Armée française de la Libération). It was well equipped and well supplied despite the economic disruption brought by the occupation thanks to Lend-Lease and grew from 500,000 men in the summer of 1944 to over 1,300,000 by V-E day, making it the fourth largest Allied army in Europe.
The French 2nd Armoured Division, part of the Free French forces that had participated in the Normandy Campaign and had liberated Paris, went on to liberate Strasbourg on 23 November 1944, thus fulfilling the Oath of Kufra made by General Leclerc almost four years earlier. The unit under his command, barely above company size when it had captured the Italian fort, had grown into an armoured division. The I Corps was the spearhead of the Free French First Army that had landed in Provence as a part of Operation Dragoon. Its leading unit, the French 1st Armoured Division, was the first Western Allied unit to reach the Rhône (25 August), the Rhine (19 November) and the Danube (21 April 1945). On 22 April, it captured the Sigmaringen enclave in Baden-Württemberg, where the last Vichy regime exiles were hosted by the Germans in one of the ancestral castles of the Hohenzollern dynasty.
By the end of the war, some 580,000 French citizens had died (40,000 of these by the western Allied forces during the bombardments of the first 48 hours of Operation Overlord). Military deaths were 92,000 in 1939–40. Some 58,000 were killed in action from 1940 to 1945 fighting in the Free French forces. Some 40,000 malgré-nous ("against our will", citizens of the re-annexed Alsace-Lorraine province drafted into the Wehrmacht) became casualties. Civilian casualties amounted to around 150,000 (60,000 by aerial bombing, 60,000 in the resistance, and 30,000 murdered by German occupation forces). Prisoners of war and deportee totals were around 1,900,000. Of these, around 240,000 died in captivity. An estimated 40,000 were prisoners of war, 100,000 racial deportees, 60,000 political prisoners and 40,000 died as slave labourers.
German casualties are hard to determine but commonly accepted figures are: 27,074 killed, 111,034 wounded and 18,384 missing. German dead may have been as high as 49,000 men, due to additional non-combat causes, wounded who died and missing who were confirmed dead. The battle for France had cost the Luftwaffe 28 percent of its front line strength, some 1,236–1,428 aircraft were destroyed (1,129 to enemy action, 299 in accidents). A further 323–488 were damaged (225 to enemy action, 263 in accidents), making 36 percent of the Luftwaffe strength lost or damaged. Luftwaffe casualties amounted to 6,653 men, including 4,417 aircrew; of these 1,129 were killed and 1,930 were reported missing or captured, many of whom were liberated from French prison camps upon the French capitulation. Italian casualties amounted to 631 or 642 men killed, 2,631 wounded and 616 reported missing. A further 2,151 men suffered from frostbite during the campaign. The official Italian numbers were compiled for a report on 18 July 1940, when many of the fallen still lay under snow and it is probable that most of the Italian missing were dead. Units operating in more difficult terrain had higher ratios of missing to killed but probably most of the missing had died.
According to the French Defence Historical Service, 85,310 French military personnel were killed (including 5,400 Maghrebis), 12,000 missing, 120,000 wounded and 1,540,000 prisoners (including 67,400 Maghrebis). Some recent French research indicates that the number of killed was between 55,000 and 85,000, a statement of the French Defence Historical Service tending to the lower end. In August 1940, 1,540,000 prisoners were taken into Germany, where roughly 940,000 remained until 1945, when they were liberated by advancing Allied forces. At least 3,000 Senegalese Tirailleurs were murdered after being taken prisoner. While in German captivity, 24,600 French prisoners died; 71,000 escaped; 220,000 were released by various agreements between the Vichy government and Germany; several hundred thousand were paroled because of disability and/or sickness. Air losses are estimated at 1,274 aircraft destroyed during the campaign. Britain had fewer than 10,000 killed in action (including the Lancastria disaster), for a total casualty figure of 68,111 men; about 64,000 vehicles destroyed or abandoned and 2,472 guns destroyed or abandoned. RAF losses in the campaign from 10 May – 22 June, amounted to 931 aircraft and 1,526 casualties. The British also lost 243 ships to Luftwaffe bombing in Dynamo, including 8 destroyers and 8 troopships. Belgian losses were 6,093 killed and wounded; some 2,000 prisoners of war died in captivity and more than 500 were missing. Those captured amounted to 200,000 men. Belgian wounded amounted to 15,850. They also lost 112 aircraft. Polish losses were around 5,500 killed and wounded; nearly 13,000 troops of the 2nd Infantry Division were interned in Switzerland for the duration of the war, and 16,000 were taken prisoner.
Hitler had expected a million Germans to die in conquering France; instead, his goal was accomplished in just six weeks with only 27,000 Germans killed, 18,400 missing, and 111,000 wounded, a little more than one third of the total German casualties in the Battle of Verdun during World War I. The unexpectedly swift victory resulted in a wave of euphoria among the German population and a strong upsurge in war-fever. Hitler's personal popularity reached its peak with the celebration of France's capitulation on 6 July 1940:
If an increase in feeling for Adolf Hitler was still possible, it has become reality with the day of the return to Berlin," commented one report from the provinces. "In the face of such greatness," ran another, "all pettiness and grumbling are silenced." Even opponents to the regime found it hard to resist the victory mood. Workers in the armaments factories pressed to be allowed to join the army. People thought final victory was around the corner. Only Britain stood in the way. For perhaps the only time during the Third Reich there was genuine war-fever among the population.
On 19 July during the 1940 Field Marshal Ceremony, at the Kroll Opera House in Berlin, Hitler promoted 12 generals to the rank of field marshal.Walther von Brauchitsch, Commander in chief of the Heer (i.e. the land warfare force of the Wehrmacht, equivalent to the British Army)
Wilhelm Keitel, Chief of Staff of the OKW
Gerd von Rundstedt, Commander in chief of Army Group A
Fedor von Bock, Commander in chief of Army Group B
Wilhelm von Leeb, Commander in chief of Army Group C
Günther von Kluge, Commander of the 4th Army
Wilhelm List, Commander of the 12th Army
Erwin von Witzleben, Commander of the 1st Army
Walther von Reichenau, Commander of the 6th Army
Albert Kesselring, Commander of Luftflotte 2 (Air Fleet 2)
Erhard Milch, Inspector General of the Luftwaffe
Hugo Sperrle, Commander of the Third Air Fleet
This number of promotions to what had previously been the highest rank in the Wehrmacht (Hermann Göring, Commander in chief of the Luftwaffe and already a Field Marshal, was elevated to the new rank of Reichsmarschall) was unprecedented. Throughout the whole of the First World War, Kaiser Wilhelm II had promoted only five generals to Field Marshal.